with every step. so he does that by pulling back like that, doesn't he? watch that sometime. most birds walk like that, monkeys too. a monkey can lean way over and grab things and move with grace, because the monkey got that big tail and that tail stick up, and that tail makes the center of gravity come over the feet. so the monkey reaches over with both hands. the center of gravity right above its feet, counterbalance, keeps the center of gravity always above the point of support. really nice. see, a lot of animals have tails. remember the dinosaurs with those huge, huge tails? when they stand up and run there, they run-- a great, big body, huh? but the other part of the tail out here, yeah, center of gravity right there. hey, they got to have the-- cut off the tail, what's that dinosaur gonna do? you know, i mean, he can't make it, huh? [laughter] i mean... a pregnant lady. yeah. you're in san francisco. and when you're in san francisco, you're in one of those hills, the famous hills in san francisco. in the famous hills, you have a bunch of trucks.